1. Field of the Invention
The present invention relates to an electronic apparatus such as a portable computer or a portable word processor, and more particularly to the housing of the apparatus, designed to contain circuit board each having circuit parts mounted on it and also to contain various functional components such as a floppy disk drive and a hard disk drive.
2. Description of the Related Art
In recent years, a variety of notebook-type portable, high-performance computers have been provided. Each of these computers comprises a base unit which has a keyboard, and a display unit which is a plat panel type hinged to the base unit and rotatable between a closed position and an open position. The base unit further comprises a box-like housing made of synthetic resin. The housing contains functional components such as a floppy disk drive and a hard disk drive, and also contains circuit board each with various circuit parts mounted on it.
Recently it is demanded that the housing of portable computers be made as small as possible so that the computers may be easier to carry and handle. Particularly it is desirable that the housing be as small and shallow as possible. The size of the circuit board to incorporated into the housing is limited inevitably, but height of the housing is not much limited. Hence, a new type of a portable computer has been developed, which comprises a plurality of small circuit boards, not a single large one, are arranged one above another within a housing and electrically connected to one another. An example of such a computer is disclosed in U.S. patent application Ser. No. 08/107,948 filed Aug. 16, 1993, S. Youji et al.
Among the parts mounted on each of those circuit board are one which generate high-frequency noise while operating. As is known in the art, if the high-frequency noise leaks out of the housing, it will cause interference of electromagnetic waves or obstruction of communication. To prevent the noise from leaking from the housing, the housing has a shield frame which functions not only as support for the circuit boards but also as an electric-wave shield.
However, the shield frame must have passages for avoiding interference between the shield frame and the supports of the circuit boards and the parts thereof. To be more specific, the shield frame needs to have many bent and held-up portions and also many through holes. Consequently, the shape of the shield frame is much complicated.
Generally, the more complicated the shape of a shield frame is, the more complex the structure of a mold for forming the frame, and the longer the time required for producing the frame. As a result, the manufacturing cost of the frame will increase. Furthermore, the shield frame must be strong enough to support the circuit boards each having a number of parts mounted on it. The frame should, therefore, have a large wall thickness. Hence, the shield frame is unavoidably heavy and large, making it difficult to make the computer as light and small as is desired.
More and more types of portable computers are being provided, in which there can be installed a memory card for increasing data storage capacity, an interface card for achieving communication with external devices, or an application card storing an application program. Each of these portable computers has a card receptacle located within the housing. The card receptacle has an insertion port which opens to a slot made in one side of the housing, and contains a card connector. The card connector is mounted on a circuit board. Therefore, this circuit board opposes the card receptacle, and a connector section connecting the parts and wiring patterns on the board are exposed to the card receptacle.
If anything electrically conductive material happens to enter the card receptacle through the insertion port while a card is being inserted into the card receptacle or removed therefrom, it may move through the card receptacle and may reach the circuit board. Thus, the conductive material may contact the connector section, inevitably causing short circuiting between the circuit parts and the wiring patterns. The short circuiting will lead to malfunction and troubles in the portable computer.
A high-performance portable computer is designed to be used in combination with a variety of external devices. Known as such external devices are a mouse and a track ball, each being a kind of a pointing device, and also an external keyboard. In many cases, these external devices are connected to the portable computer in different ways, though they are designed to perform the same function, that is, the function of inputting data.
More precisely, pointing devices such as mouses are divided into two types. The first type is to be connected to the computer by means of a cable. The second type is to be connected directly to the connector attached to the computer. As for external keyboards, there are various types to be connected to the computer by different kinds of interface connectors. This is why the high-performance portable computer has a plurality of interface connectors of different specifications. In many cases these interface connectors are arranged in the same plane in the computer.
Thus, two or more external devices of the same function can be connected to the computer by means the interface connectors. It follows that the signals generated in these external devices may supplied to the computer at the same time and may therefore interfere with one another in the computer. Such signal interference occurs, if any occurring, will cause malfunction and troubles in the portable computer.
As is disclosed in U.S. Pat. No. 5,081,742 issued Jun. 21, 1992 to T. Kobayashi and U.S. Pat. No. 5,103,377 issued Apr. 7, 1992 to T. Kobayashi et al., the display unit of a portable computer is hinged to the housing and can be rotated between a closed position and an open position. At the closed position, the display unit covers the keyboard of the computer. At the open position, the unit stands upright at the rear of the keyboard. More specifically, the display unit has a pair of legs, and the housing has two leg-holding recesses. The legs are fitted in the recesses, respectively, and are rotatably connected to the housing by a hinge mechanism. The hinge mechanism has a hinge shaft which extends through the housing and both legs of the display unit, passing through the hole made in the side surface of the leg-holding recesses.
Each leg-holding recess has an opening open to the interior of the housing. The opening has a bottom opening portion and a side opening portion continuous with the bottom opening portion. The bottom opening portion is made in the bottom surface of the leg-holding recess, and the side opening portion is made in the side surface of the leg-holding recess. The opening closed by cover fastened to the inner surface of the housing by means of screws. The cover has a bottom wall covering the bottom opening portion, and a side wall covering the side opening portion. The side wall cooperating with the side opening portion to form the hole, and the hinge shaft passing through the hole.
Screws are required to fasten the covers to the housing, increasing the number of parts indispensable to the housing. In addition, the housing needs to have bosses for engagement with the screws, and has a structure more complex than otherwise. The increase in the number of necessary parts and the complex structure of the housing raises the manufacturing cost of the housing.
As disclosed in U.S. Pat. No. 5,111,361 issued May 5, 1992 to T. Kobayashi, a portable computer has a tilt mechanism which holds the keyboard in such an inclined position that an operator can operate the keyboard with ease. The tilt mechanism is mounted on the bottom of the rear part of the housing. It comprises a support, a slider and a stand. The support is formed on the bottom of the housing. The slider is supported by the support and can slide up and down. The stand is rotatably connected to the lower end of the slider. Rotatably coupled to the slider capable of moving vertically, the stand can be moved vertically, and can also be rotated back forth, with respect to the housing. The stand can be moved between a first position where it protrudes downwards from the bottom of the housing, and a second position where it is held parallel to the bottom of the housing.
To tilt up the keyboard of the computer, the operator first holds the rear of the housing upwards, then rotates the stand downwards from the second position, and finally pushes the stand upwards until the junction of the stand and the slider fits into the support. Once the junction has fitted into the support, the stand is held in the first position.
In order to move the stand from the first position into the second position, the operator pulls the stand downwards, releasing the junction of the stand and the slider from the support. Next, the operator rotates the stand forward so that the stand may be held parallel to the bottom of the housing. The stand is thereby fitted into a recess formed in the bottom of the housing. As a result, the stand is held in the second position.
Whether to set the stand into the first position or the second position, the operator needs not only to slide the stand but also to rotate the stand. The operator can move the stand into neither position, with a one-touch operation. Thus, the tilt mechanism needs to be modified to improve its operability.
As disclosed in U.S. Pat. No. 5,068,652 issued Nov. 26, 1991 to T. Kobayashi, a portable computer has an indicator for showing the condition in which the computer is operating. The housing of the computer has a projection having a rectangular cross section. A plurality of display holes are made in the corner defined by the front and the top of the projection. In these holes there are fitted display lenses for allowing passage of light. Each lens is exposed at both the front of the projection and the top thereof.
The projection contains light-emitting diodes for applying light to the display lenses. These diodes are located near the lenses so that they may apply light with high efficiency. The light-emitting diodes are mounted on a circuit board. The circuit board is arranged within the projection, extending substantially in parallel to the top of the housing. The circuit board is isolated from the main circuit board incorporated in the housing, and is designed exclusively to drive the light-emitting diodes.
The circuit board on which the light-emitting diodes are mounted is indispensable, exclusively for supporting these diodes. Furthermore, connectors and cables are required, electrically connecting this circuit board to the main circuit board. The number of necessary parts is unavoidably increases, raising the manufacturing cost of the portable computer. The more light-emitting diodes are arranged side by side in the projection, the longer will this circuit board which is arranged in the projection and supports these diodes, and the larger the space in the projection. This would hinder the downsizing of the housing.
The housing of a portable computer is compact as a whole so that the computer may be easy to carry and handle. Within the compact housing, functional devices such as a floppy disk drive and a hard disk drive, and circuit board each having various parts are arranged in high density. The functional devices are electrically connected to the circuit board by cables. In many cases the cables are placed in the gaps among the adjacent functional devices. Made slender and flexible, the cables can hardly be held straight and may bend themselves to project from those gaps. It usually takes much time and labor to install the cables in the housing of the portable computer.